That poster pulled off the trick of making a fairly abstract economic issue like the national debt into an emotive, personal issue directly relevant to individuals. It is said to have been particularly effective with younger women.

It is also the foundation of all Conservative attacks on Labour to this day: the Opposition would spend too much, saddle you and your country with debt, and generally make things worse.

It's a sign of successful that attack has been that the respectable macroeconomic debate about whether deficit spending in an era of low growth and low interest rates is or is not a bad thing is almost wholly absent from British politics: for politicians and most voters, deficits are bad, debt is bad. End of story.

So you can understand why Mr Cameron wants to repeat the trick. In Nottingham today, he put it thus: "To every mother, father, grandparent, uncle, aunt – I would ask this question. When you look at the children you love, do you want to land them with a legacy of huge debts?"

But there's a difference between now and 2010. Mr Cameron has been in office since 2010. He has a record on the debt and the deficit, on which voters can judge him.

The Coalition took office in 2010 and said it wanted to clear the deficit by 2015/16. Having missed that target, Mr Cameron's plans now clear the deficit by 2018/19. That means more borrowing, borrowing that adds to the stock of public debt.

As for that national debt, here it is, expressed as a share of the economy. On current forecasts, it will peak in 2016/17 at 90 per cent of GDP, before starting to fall again. Which means Mr Cameron can credibly say that he plans to reduce the debt, at least a little bit.

And here's the debt measured in cold hard cash. Yes, it only goes one way: up.

Government debt, as Mr Cameron rightly notes, means interest payments on that debt. You pay for that interest, via your taxes.

This shows you quite how much you're going to pay for the rest of the decade.

For context, that £60 billion figure in 2019/20 is more than the Government will be spending on schools or the Armed Forces.

So by most interpretations, those beloved children Mr Cameron invokes are going to inherit a "legacy of huge debts" even under his plans.

Mr Cameron's argument, of course, is that legacy would be worse under Labour: the Opposition would borrow more and thus add more to the national debt. We don't have OBR-costed figures for Labour's plans, so it's hard to say precisely what they would mean for the national debt, but it's perfectly valid for the Conservatives to argue Labour would mean more debt; and certainly, I've so far seen no Labour promise suggesting the debt would be lower under Labour plans.

Do you accept the premise that debts and deficits are bad and should be eliminated? If so, remember that on the public finances, the choice between the Conservatives and Labour is a choice not between good and bad but between bad and worse.